


Future Knowledge

by JustWriting



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Sex, M/M, Oral Sex, Plot What Plot/Porn Without Plot, Self-cest, Time Travel
Language: English
Status: Completed
Published: 2019-10-05
Updated: 2019-10-05
Packaged: 2020-11-24 06:34:58
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,319
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20903219
Author URL: https://archiveofourown.org/users/JustWriting/pseuds/JustWriting
Summary: Sylvain's future self mysteriously ends up at the monastery and decides to give some lessons to his younger self and boyfriend.





	Future Knowledge

**Author's Note:**

> Hello! I still am unsure in my skill at writing smut but I had to do this so,,, hope you enjoy! Also, navigating through two characters with the same name was quite a task. That being said, any comments/critiques are greatly appreciated. 
> 
> Also, this takes place near a later battle- Pegasus Moon (/Felix's bday) has passed, so he is 18

Felix is having a hard time comprehending how he ended up in this situation. Sylvain and him had decided to spend the day together before their next mission. They were taking a stroll through the halls of Garreg Mach when suddenly a portal opened before them and a someone with a familiar, but older <strike>and hot</strike>, face came stumbling out. After that there was a flurry of questions and all Felix could remember was being very confused. Now somehow, he was in his bedroom wedged between the two.  
  
"Ah being back here is bringing back so many memories." Sylvain said as he began to slowly take his shirt off  
  
"_What_ are you doing?"  
  
Sylvain winked, "Just getting comfortable."  
  
As he continued to undress Felix looked at his Sylvain for help. But his brain looked fried. Felix kept giving him looks for help but he just stared at him dumbly. He began to retrace the events when the older Sylvain started working at undoing Felix’s pants.  
  
“Hey! Wh-what, stop!” Felix shouted while pulling his hands away in distress.  
  
He let out a small chuckle behind him, “You said you wanted to learn from me? Oh, perhaps you were talking about sparring?”  
  
Oh shit  
Felix instantly turned red. When he had asked to learn he didn’t mean sex. Sylvain seemed to notice this because he sat back laughing. That just proceeded to make Felix even more embarrassed. He let out a curse under his breath before looking at his Sylvain. “Please tell me you’re with me on this.”  
  
To that he just turned his head to the side blushing. “I mean, I only have experience with girls so we’ve only touched…”  
  
“You have _got_ to be kidding me!” The older Sylvain was still cracking up behind him and Felix had never been so embarrassed. “This is ridiculous. Have fun by-_with_ yourself. I’m leaving.”  
  
As he began to crawl off the bed his Sylvain grabbed his wrist. He turned towards him ready to spit out an insult but is met with Sylvain’s soft puppy eyes. He hesitates so Sylvain softly pleads, “C’mon Fe, I wanna learn how to do this right.”  
  
Felix hesitates again. Fighting Sylvain’s puppy eyes has never been easy, but he can’t get over the fact that’s he’s about to bare himself to _two_ Sylvains. As if one isn’t embarrassing enough.  
  
The older Sylvain has finally stopped laughing to himself and sits up again, “Hey, I promise I won’t do anything you dislike. After all I do know you pretty well.” He annoyingly adds a wink to that last part and Felix rolls his eyes.  
  
He stands still for a while thinking over the situation and finally sighs, “Okay I’ll do this if you only lead us through it. I’m having sex with my boyfriend. Not my future one.”  


Sylvain hums as he thinks it over. “I’ll try my best, but no promises.”  
  
Felix scowls and is ready to walk away again but his Sylvain gives a small tug on his wrist batting his beautiful eyes at him. He sits down with a frown, right in his Sylvain’s lap so that he is closer to him and lets out a sigh closing his eyes. “Okay. So future genius, what do we do first?”  
  
The second he finishes the question Sylvain reaches past Felix, pulling his younger self close so that his lips meet with Felix’s. He looks shocked at first but after a moment his eyes flutter closed and they begin softly kissing. Felix can feel heat from both the man he is kissing and the one behind him and his stomach tightens. It feels odd being watched like this by someone he is technically also dating. He decides instead to focus on Sylvain’s lips on his and deepens it while Sylvain begins slowly rubbing his thighs.  
  
By the time they break the kiss both of them are now breathing heavily, their eyes lidded. Felix had been so absorbed he didn’t even notice the Sylvain behind him had had his arms around him while rubbing his younger selfs thighs. His thumbs dangerously near his crotch.  
  
Felix blushes at the sight but doesn’t look away, “Feeling yourself? Pervert.”  
  
“Haha, well you said I couldn’t touch you so.” At that Felix shuddered. His voice was full of honey and right next to his ear. “So ready for the next step?”  
  
Felix turns his head stubbornly to the side in silence with a fake scowl, and both Sylvains know that means yes.  
  
"Okay little me, do you have experience with blow jobs yet?"  
  
"Uh, yeah I do. I mean I think I do?"  
  
Felix watched Sylvain’s reaction, the small blush of embarrassment creeping up his neck. Maybe this wasn't so bad after all. It wasn't very often he got to see Sylvain being the nervous one when they were in bed. __<strike>I suppose being around a more experienced version of yourself doesn’t build confidence</strike>  
  
"Then start giving one to Felix, I'll help you out if you need pointers."  
  
He nodded his head in agreement and pulled back with a shaky breath to bend down and begin undoing Felix pants. Once he pulled out Felix's erection, he gave it a few long pumps before kissing and licking along.  
  
Older Sylvain chuckled again from behind Felix and ran his hands through his younger selfs hair. "Hah, I forgot how long it took to give a proper blow job." He moved his hands down to cup Sylvain face and tilt his chin up. "Try taking him into your mouth Mkay?"  
  
He nodded in response and took the tip of Felix in his mouth. Felix said nothing, just shuddered in response. "Okay good, make sure you don't use your teeth. Now slowly ease down" while speaking he began slowly guiding Sylvains head lower. "Good job, now open your throat. Perfect."  
  
Once Sylvain had enough of Felix inside of him to feel him in his throat he made a small noise. The feeling sent a tremble through Felix. His older self slowly ran his hand through his hair again letting out a small hum, "Make sure you continue to breath out of your nose."   
  
This sensation was so new to Felix. To have Sylvain’s warm mouth wrapped around him, he could easily get used to this feeling. After some time his Sylvain finally began to move slowly up and down, testing how much of Felix he could take into his mouth. His older self still softly giving direction on when to change the speed or technique. _Goddess_ Felix had never felt better.  
  
While his Sylvain was busy giving him a blow job his older self slid his hands under Felix's shirt and up to his nipples. He began to circle them slowly when Felix grabbed his hands to stop him.  
  
"Aha, no. I don't do nipple play. Thought you said you knew me." Felix said as sharply as he could at that moment  
  
"Oh really?" Sylvain snickered, "You really ought to give it a chance." He said as he softly pinched Felix.  
  
That sent a jolt through his body and he slightly thrust into his Sylvains mouth. The sudden movement caused him to pull back in surprise. He blinked and looked up at Felix, catching his breath and watching what his older self was doing.  
  
"See?" Sylvain said kneading at the nipple between his fingers. "You seem to be enjoying this."  
  
"Tsk. Idiot. That was just because of the blow job." He said blushing furiously and shrugging Sylvain's hands off of him.

“Goddess Felix,” his Sylvain said breathless, some drool running down his jaw. “You look so good right now.”

Felix blushed at his words and appearance. He couldn’t believe he looked like such a mess just from giving Felix a blow job. _I could get used to this look_. He leaned forward to begin kissing him once again. As he kissed him he thought of how this mouth was just on him. It _belonged _to him. During the kiss Felix gave up. This felt too good not to give in, and dammit, it was _Sylvain_. Why not take advantage of having two?

Knowing Felix for many years both of them picked up on his shift in demeanor, so while they were busy making out older Sylvain set to work stripping them all. They briefly parted kissing to get shirts over their heads then immediately went back to one another’s lips. Once they were fully undressed Sylvain began softly kissing along Felix’s neck, and grabbed his younger selfs hand bringing it to Felix chest. This time Felix didn’t resist and instead leaned into the feeling, letting out small moans into Sylvains mouth. Sylvain finally broke the kiss to trail down Felix’s neck to his chest where he hungrily lapped at his nipples. Felix arched into the sensation and the man behind him took the opportunity to capture his mouth in a kiss, this one more desperate than the last.

The sensation was so overpowering to Felix he hardly noticed the hands running down his sides until he felt a finger circling a very sensitive part of him. He grabbed the wrist out of natural reflex, and was shocked when he saw it was his Sylvain who had initiated it.

He looked at him a little surprised and blushed, “Sorry, I should’ve asked…”

“Uhm, no. I was just a little surprised.” He’s pretty sure neither of them have ever been more red than right now.

From behind him there’s a small laugh as Sylvain nips at his neck. “You two are so adorable.”

Okay, _now _the two of them have never been more red.

Before anyone says another word older Sylvain quickly leaves the bed to rummage through his clothes, retrieving a small bottle. He tosses it to Sylvain, “here, this will make things smoother.”

As his Sylvain examines the bottle, pouring some of the contents onto his fingers Felix takes a deep breath. “So, I’m the bottom?”

At that he pauses, “Do you not want to?”

“it’s not that it’s just...” as he stops talking his eyes trail down to Sylvains dick. He’d be lying if he said the size didn’t concern him.

Thankfully the man behind him seems to read his concern well because he chimes in, “don’t worry, that’s why I’m here to help.” Though much to Felix annoyance he still adds on a wink. _I can’t believe he still does that. _ “As long as you guys prepare it’ll be just fine.”

“Okay,” his Sylvain lets out a shaky breath. Then trying to mask it, “it shouldn’t be too different right? I mean I’ve-“

“Sylvain, if you say another word I’ll kick you out and fuck your future self.”

Older Sylvain lets out a genuine laugh while the other laughs nervously, “Aha, right my bad.” With that he moves on focusing once again on Felix’s ass. He begins tentatively feeling around while the other two watch. “Okay Fe, relax.”

Felix let’s out a slow breath as Sylvain slowly pushes his first finger into him. He’s met with little resistance he proceeds to slowly pull out. At that sensation Felix tenses up, “_fuck” _and Sylvain immediately pauses and looks up. The feeling is so new to Felix, it doesn’t feel bad, but it’s not exactly pleasurable either.

“You’ve got to relax babe, it’ll feel really good.” His older self says beginning to plant soft kisses on Felix’s temple while rubbing soothing circles into his thighs. When he feels him relax back into his arms he glances over, “you can keep going now. He wasn’t in pain, just surprised.”

Felix blushes at the fact he could read him so easily. “Fuck you”

He laughs, “After your turn is done, go ahead.”

Felix just curses again but decides to ignore him and focus on the sensation of Sylvains finger. After awhile he is able to add more, slowly working him open and Felix can feel pleasure begin to build inside of him. Small whimpers and moans begin escaping Felix’s mouth as Sylvain continues to thrust into him, periodically scissoring his fingers apart while he plants long wet kisses along his thighs.

By the time Sylvain says Felix is prepared enough all three of them are painfully hard. Felix can feel himself slipping away from reason. Through the whole process both Sylvains continue to praise him. Saying how good he’s doing in those sweet honey filled voices while their hands run across every inch of his body.

His Sylvain pulls his finger out and Felix whimpers at the loss. His Sylvain hums while moving back to admire the view and slowly stroke himself before continuing. Felix, however, is dying to know what Sylvain feels like. He thrusts his hips into the air, “Sylvaaaain, stop making me wait.” The words come out more desperate and less threatening than he had hoped.

His Sylvain lets out a soft laugh, but the one behind him let’s out a small surprised gasp when Felix’s hips come back down to the mattress, pressing into him in the process. Felix had been sitting against him for awhile but was just now realizing _how_ hard he’d gotten. Smirking he pushes his hips back into him again and Sylvain shudders at the feeling, gripping his hips.

His Sylvain smiles at the scene while beginning to slowly rub his dick against Felix’s ass, “God that’s so hot.” The feeling causes Felix to slowly grind his hips back into the man behind him, whose grip tightens on his hips.

Sylvain begins lightly rutting against Felix now and whispers into his ear, “Tell my younger self what you want Felix.” He nips at his collarbone, “What do you want him to do?”

Felix shudders, his eyes now lidded and full of want, and reaches out to his Sylvain pulling his face down towards him, “Sylvain, fuck me. Please.”

At that he smiles and kisses Felix, “Since you said please.” He begins slowly pushing into him, and as he goes further Felix gasps, opening his mouth up further for Sylvain to explore with his tongue. Eventually Sylvain makes it to the base and pauses for a moment. Felix has never felt so full and its amazing. The two of them are desperately kissing one another while the older Sylvain continues his small movements against Felix.

They finally break the kiss gasping for air and his Sylvain rests his forehead on his shoulder panting, “Felix, you feel so good. You’re so good.”

Felix tightens at the praise and it causes Sylvain to let out a moan. “Sy-Sylvain… move.” He doesn’t need to be told twice and he slowly begins moving in and out of Felix, both of them adjusting to the new sensation.

“Hmm, looks like it’s time for a few more lessons,” Older Sylvain says, voice full of arousal. He moves back, slowly laying Felix flat on the bed and moves to sit next to his younger self for a better view. “It’s not just about going in and out. For example, try pulling out slowly, all the way to the tip.”

Sylvain does as he’s told, pulling out with a shaky breath as Felix arches his back slightly. “Good job” he purrs before grabbing Sylvain’s waist and suddenly pushing him back into Felix without warning. The two of them both let out a loud moan as he’s buried deep inside once more.

Felix gasps, “Fuck Sylvain, what was that!?”

He gives a cocky smirk, “Did it feel good?”

“Goddess, it was amazing,” his younger self answers. “Did it feel good for you Fe?”

He reaches up and strokes Felix’s face loving with one hand while his other rubs at the tip of his cock. He just blushes in response before mumbling, “you can keep going.”

After that they continue to fuck, Sylvain keeps giving tips throughout the process until the two can hardly process what he’s saying to them anymore. He’s changed their position so that each thrust is now hitting just right in Felix, turning him into a moaning drooling mess. Now with each movement all that comes out of Felix’s mouth are broken gasps and fragments of Sylvains name.

His Sylvains movements become erratic as he nears his orgasm, “ F-Fe, Felix- I’m so close”

Felix wraps his arms around Sylvain’s neck bringing his face to his as he continues to thrust into him, “me too, I’m so close Sylvain.” They look at one another’s faces, desperate and flushed, as they are nearing their release and hungrily bite and suck at each other’s lips until they both freeze. The noises that poor out of them are heavenly as Sylvain gives his last few thrusts while they ride out their orgasms before collapsing. They are both breathing heavily as they come down from their high. Felix’s ass squeezing every last drop from Sylvain as Felix’s last streaks of cum dribble out of him onto his stomach.

Beside them older Sylvain lets out a whistle, “Fuck, that was hot.” They look over at him as he is pumping his dick.

“Oh, you haven’t cum yet?” Felix says lazily, still not quite back to his normal quick thinking. If he was, he’d definitely have something to say about the scene before him, or what started happening next.

His Sylvain sat up, his dick slipping out of Felix, and crawled over to his older selfs lap moving his hands aside. “Wanna see how well you taught me?” He teasing winked up, grasping him in his hands before running his tongue along the throbbing underside.

“Damn, I really didn’t change,” Sylvain chuckled, before grabbing a handful of hair and pushing him down onto his cock. Felix blinked in surprise at the sight. It was sloppy and wet, as both Sylvains made noise, and Felix found himself getting irritated for some reason. <strike>There’s no way in hell I’m jealous of Sylvain for blowing Sylvain. </strike>

He had regained his stubbornness but not all his thoughts as he climbed over to be next to them and pushed his Sylvain off of the others dick before plunging down on it himself.

Sylvain let out a moan as Felix’s mouth wrapped around him, sucking him just like he’d told his younger self to do earlier.

“Hahhh Felix,” he said while his head tilted back, “you always were a quick study.”

Felix just hums in response and it sends shivers down Sylvains spine. He now runs his hand through Felix’s hair, his bun barely in anymore as strands are falling everywhere. His other hand is still running through his younger selfs hair and he tugs him into a kiss. Felix stops sucking his cock to look up and watch, only running his tongue along the side. After a moment Sylvain pushes his younger self back down between his legs next to Felix.

“I’m about to come, how about you two work together as thanks for today’s lesson?” he says, lovingly stroking their faces.

The two don’t respond, instead going straight to work licking all along his cock. Their breaths mingle together as they hungrily lap up one another’s spit, mixed with Sylvains precum. Occasionally taking turns to take him into their mouth and down their throat.

Then, without warning, Sylvain is cuming. The two of them pause shocked, while Sylvain growls grabbing his dick to stroke it, riding out the orgasm. Once he’s done the two of them have the mess all over their faces.

Sylvain takes in the sight and smiles at them. He’s opening up his mouth to comment on how hot they look but is cut off.

“_Sylvain,_” Felix scowls, “_Clean me up right this instant.”_  


Older Sylvain pauses for a moment then falls back onto the mattress laughing. Felix fumes and is about to yell until his Sylvain pulls his head towards him and licks at some of the cum on his face. “Don’t worry Fe,” he sooths lovingly <strike>and seductively. </strike>“I’ll clean you up." 


End file.
